Add observer interface to PrerenderContents.

chrome/browser/prerender/prerender_contents.h

Index: chrome/browser/prerender/prerender_contents.h
diff --git a/chrome/browser/prerender/prerender_contents.h b/chrome/browser/prerender/prerender_contents.h
index 7461937ef0e3dc2a121b8ba334be77ce3fa462b4..e0fa2c02ee0dfc27c79da8da929037a4ed05e5f5 100644
--- a/chrome/browser/prerender/prerender_contents.h
+++ b/chrome/browser/prerender/prerender_contents.h
@@ -9,6 +9,7 @@
 #include <utility>
 #include <vector>
 
+#include "base/observer_list.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
@@ -45,7 +46,6 @@ namespace prerender {
 class PrerenderHandle;
 class PrerenderManager;
 class PrerenderRenderViewHostObserver;
-class PrerenderTracker;
 
 class PrerenderContents : public content::NotificationObserver,
                           public content::WebContentsObserver {
@@ -61,7 +61,6 @@ class PrerenderContents : public content::NotificationObserver,
     // prerender_tracker, and profile are stored as weak pointers.
     virtual PrerenderContents* CreatePrerenderContents(
         PrerenderManager* prerender_manager,
-        PrerenderTracker* prerender_tracker,
         Profile* profile,
         const GURL& url,
         const content::Referrer& referrer,
@@ -72,6 +71,19 @@ class PrerenderContents : public content::NotificationObserver,
     DISALLOW_COPY_AND_ASSIGN(Factory);
   };
 
+  class Observer {
+   public:
+    // Signals that the prerender has started running.
+    virtual void OnPrerenderStart(PrerenderContents* contents) = 0;
+
+    // Signals that the prerender has stopped running.
+    virtual void OnPrerenderStop(PrerenderContents* contents) = 0;
+
+   protected:
+    Observer();
+    virtual ~Observer() = 0;
+  };
+
   // A container for extra data on pending prerenders.
   struct PendingPrerenderInfo {
    public:
@@ -116,6 +128,10 @@ class PrerenderContents : public content::NotificationObserver,
 
   virtual ~PrerenderContents();
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+  void ClearObservers();

[mmenke, 2012/12/03 20:02:47]

ClearObservers() doesn't seem to have a function body, and seems like, in
general, a bad idea anyways, so I think we should remove it.

[gavinp, 2012/12/04 18:04:48]

Done.

+
   // For MatchComplete correctness, create a dummy replacement prerender
   // contents to stand in for this prerender contents that (which we are about
   // to destroy).
@@ -147,6 +163,8 @@ class PrerenderContents : public content::NotificationObserver,
   content::RenderViewHost* GetRenderViewHostMutable();
   const content::RenderViewHost* GetRenderViewHost() const;
 
+  PrerenderManager* prerender_manager() { return prerender_manager_; }
+
   string16 title() const { return title_; }
   int32 page_id() const { return page_id_; }
   GURL icon_url() const { return icon_url_; }
@@ -254,13 +272,17 @@ class PrerenderContents : public content::NotificationObserver,
 
  protected:
   PrerenderContents(PrerenderManager* prerender_manager,
-                    PrerenderTracker* prerender_tracker,
                     Profile* profile,
                     const GURL& url,
                     const content::Referrer& referrer,
                     Origin origin,
                     uint8 experiment_id);
 
+  // These call out to methods on our Observers, using our observer_list_.
+  void NotifyPrerenderStart();
+  void NotifyPrerenderStop();
+  void NotifyPrerenderAddAlias(const GURL& alias_url);

[mmenke, 2012/12/03 20:02:47]

NotifyPrerenderAddAlias is not currently implemented, and there's no
corresponding observer function.

[gavinp, 2012/12/04 18:04:48]

Done.

+
   // Called whenever a RenderViewHost is created for prerendering.  Only called
   // once the RenderViewHost has a RenderView and RenderWidgetHostView.
   virtual void OnRenderViewHostCreated(
@@ -303,12 +325,11 @@ class PrerenderContents : public content::NotificationObserver,
   // Returns the ProcessMetrics for the render process, if it exists.
   base::ProcessMetrics* MaybeGetProcessMetrics();
 
+  ObserverList<Observer> observer_list_;
+
   // The prerender manager owning this object.
   PrerenderManager* prerender_manager_;
 
-  // The prerender tracker tracking prerenders.
-  PrerenderTracker* prerender_tracker_;
-
   // The URL being prerendered.
   GURL prerender_url_;